Essay on Plant Structure

Submitted By ayymayys
Words: 1311
Pages: 6

Vascular Plant Structures

Structures of vascular plants (tracheophytes)
• Organ systems and organs
• Tissues
• Cells
• Two organ systems: shoot system and root system
• Shoot system contain leaves, stem, flower, and fruit or cone
• Root system is where roots are
• Bryophytes: liverworts, hornworts, mosses
• Tracheophytes: o Seed-
• angiosperms, flowers, fruit, broad leaves
• gymnosperm: cones, needle leaves o Non-seed- ferns (spores)

Stem Functions
• Support: maximize photosynthesis
• Conduction: xylem (for water/nutrients) and phloem (for carbohydrates)
• Secondary growth in dicots: meristems in stems produce new cells
• Storage: carbohydrates, water
• Nodes are where active cell division is happening

Stem Form: Tuber
• Below ground, fleshy, enlarged
• Eyes = nodes

Stem Form: Rhizome
• Below-ground, horizontal

Stem Form: Stolon (runners)
• Typically above-ground, horizontal

Stem Form: Fleshy storage system
• Cactus

Leaves- Functions
• Photosynthesis- Co2 + light + chlorophyll > O2 + carbohydrates
• Transpiration- evaporation of H2O
• Storage- cotyledons (not “true” leaves)
• Protection- bracts, scales, and spines are modified leaves
Leaves – Functions
• Bracts: specialized function is to make the whole plant look like one big flower and attract pollinators

• Reproduction o Pollination o Fertilization o Fruit o Seed
• Flowers can be produced annually, biannually, every 15 to 100 years
• Pistil: female reproductive organ of a flower, can only be in angiosperms o Stigma o Style o Ovary
• Stamen: male reproductive organ of an angiosperms o Anther: carries pollen o Filament
• Typically there are multiple stamens and a single pistil
• Flower classification based on reproductive parts o Perfect flower (hermaphroditic): both male and female reproductive parts present in the same flower o Imperfect flower: has either male or female reproductive parts
• Pistillate- female flower
• Staminate- male flower

• Functions: o Protection of developing seeds o Seed dispersal- animal, wind, water
• What is a fruit, botanically? o Mature ovaries of flowers o Ovary- can be fleshy (edible portion) o Ovules- fertilization results in seed
• Animal dispersed fruits tend to be fleshy with appendages
• Wind dispersed fruits are small, lightweight, and have “wings”
• Water dispersed fruit have a waxy covering and float easily

Root Anatomy
• Monocot roots have a ring like arrangement
• Dicot roots have a cross like arrangement
• When roots are coming out of areas where they typically aren’t supposed to be, they are called adventitious roots.
• Functions of roots: o Anchoring o Absorption (niche exploration) o Conduction o Storage
• Tuberous roots- not the same as stem tubers!
• Mycorrhizae (myco- fungus, rhizae- roots): when roots and fungi live together in symbiosis (95% of plants can’t exist without doing it) o Benefits: expanded root system for the plant; o Benefit for the fungus: access to carbohydrates and shelter for reproduction for the fungus

Photosynthesis *Plants are primary producers. • The discovery that some animals have found ways to feed off the Sun’s energy has led to the intriguing idea that humans could one day create solar-powered nourishment. Photosynthesis
• Capture of solar energy
• Production of complex organic molecules = 2 carbohydrates (CHO)
• Conversion of light energy into chemical energy o Use light energy to make chemical energy
• 6CO2 + 12H2O + chlorophyll + light → C6H12O6 + 6O2 + 6H2O o 6CO2 = carbon dioxide o C6H12O6 = carbohydrates
• Where does photosynthesis happen? o Presence of functional chloroplast and chlorophyll will allow photosynthesis to happen o Leaves - primarily
• Chlorophyll is located within chloroplasts in plant cells o Factors that can affect photosynthesis
• Water
• Light
• Carbon dioxide